We propose to advance the use and interpretation of near-infrared spectroscopy (NIRS) technology by determining the faithfulness to which NIRS localizes patterns of blood flow relevant to addiction-related processes. Importantly, these NIRS signals will be simultaneously collected with behavioral measures of addiction (e.g., self-administration) in real-time. Currently, the use of functional magnetic resonance (fMRI) for the study of small mammals is difficult and relatively impractical for the majority of researchers. Our goal is to provide a poor man's functional imaging device that will be available for a modest cost and is readily accessible and easy to implement. Simply stated, our intent is to rapidly increase our knowledge base about blood flow changes in animals that could be readily translated to understanding human processing of drug-related information. In the proposed research, we will use a multi-faceted approach including NIRS, MFI, and intravenous self- administration of cocaine to determine whether localized assessment with NIRS is a useful alternative to fMRI to determine changes in blood flow. We will extend the utility of the NIRS approach to freely moving animals that are actively self-administering cocaine. Both the significance and innovation of this approach is relevant for the CEBRA due to the development of innovative technology to rapidly advance our understanding of blood flow change in animal models. Aims Proposed: * Specific Aim 1. To establish the similarities in blood flow changes detected by fMRI and NIRS. * Specific Aim II: To determine whether we can use NIRS to monitor neuronal activity in real-time in freely moving animals.